Light anti-chipping coating

ABSTRACT

A light anti-chipping coating consisting of vinyl chloride plastic sol is manufactured by employing a hollow filler as a small portion of the overall filler component. Doing so permits weight reduction without deteriorating the anti-chipping property of the light anti-chipping coating.

This application is a continuation of U.S. Ser. No. 07/193,718, filedMay 13, 1988, abandoned, which is a continuation-in-part of U.S. Ser.No. 06/922,606, filed Oct. 24, 1986, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a light anti-chipping coating obtained bysubstituting organic hollow filler and/or inorganic hollow filler for asmall portion of the filler component of an anti-chipping coating basedon a vinyl chloride plastisol.

2. Description of the Prior Art

Recently, anti-chipping coatings consisting of vinyl chloride plastisols(hereinafter referred to as VCPS) are employed in lieu of conventionalasphalt series undercoat materials to coat such vehicle parts as a sideseal, a fuel tank, a front apron and a tire house, using an airlesscoating apparatus, in order to protect these parts from damage that mayotherwise be caused by stones striking them during running of thevehicle.

As for the technology of using hollow fillers, there are hollow fillersused as a filler component of baking type sound-proof coatingsconsisting of rubber component and filler component (as disclosed inJapanese Patent Laid-Open 55-58261) and hollow fillers in rubber asphaltemulsion in a method of sound/vibration prevention using a coatingconsisting of rubber asphalt emulsion and solidifying agent (asdisclosed in Japanese Patent Laid-Open 60-87879).

There has been growing demands for increasing the area of coating andthickness of coating films of anti-chipping coatings consisting of theVCPS noted above in order to extend the life of vehicles and improve thelevel of the rust-proof requirements.

Such measures, however, increase the weight of the vehicle and are henceundesired from the standpoints of the running performance and energysaving through weight reduction of the vehicle.

SUMMARY OF THE INVENTION

The present invention has an object of providing a light anti-chippingcoating, which is small in grain size and light in weight withoutdeteriorating at all the anti-chipping performance per unit volume ofthe coating.

Another object of the invention is to provide a light anti-chippingcoating, which can be coated without coating irregularities and whichcan reduce gear of piston section and tip section of a coatingapparatus.

The invention is based on a finding that by employing a hollow filler toreplace a small portion of the filler in the manufacture of ananti-chipping coating based on VCPS, it is possible to obtain aVCPS-based anti-chipping coating, which is light in weight, can becoated without coating irregularities and can reduce wear of the pistonsection and tip section of coaters while ensuring anti-chippingperformance comparable to that of the prior art anti-chipping coatings.

The invention features a light anti-chipping coating, which is obtainedby a process comprising dispersing a vinyl chloride resin in aplasticizer and adding filler including a hollow filler and additives tothe dispersoid.

The vinyl plastisol comprises 100 parts by weight of a vinyl chlorideseries resin, from 50 to 200 parts by weight of a plasticizer for saidresin, from 80 to 350 parts by weight of a filler and from 2 to 20 partsby weight of other additives.

The hollow fillers are low in bulk specific gravity compared withconventional fillers used for anti-chipping coatings.

Thus, it is possible to reduce the bulk specific gravity of theanti-chipping coating incorporating them from values of 1.35 to 1.55 tovalues of 0.90 to 1.15, i.e., by 0.3 to 0.6.

Further, the substitution of the hollow filler for a small portion ofthe conventional filler component never leads to deterioration of theperformance of the anti-chipping coating or like deficiency.

The VCPS is obtained by dispersing a vinyl chloride resin in aplasticizer and adding a filler and various additives.

Suitable examples of the vinyl chloride series resins are homo-polymerssuch as polyvinyl chloride, polyvinylidene chloride and the like andcopolymers comprising vinyl chloride, vinyl acetate, vinylidene chlorideand the like.

Suitable examples of the plasticizer are a phthalic acid ester, an esterof dibasic acid, a phosphoric acid ester and polyester plasticizers, anddioctyl phthalate (DOP) is particularly preferred.

Examples of the conventional filler are talc, calcium carbonate,diatomaceous earth, mica, kaolin, barium sulfate, magnesium carbonate,graphite, alumina, silica, rubber thermoplastic resin and the like.

These fillers are in the form of powder.

Further, it is possible to employ such coloring agents as titaniumoxide, carbon black, and the like.

The hollow filler which is incorporated as an indispensable constituentof the present invention may be either organic or inorganic.

Examples of the organic hollow fillers are fillers made of polyolefinseries resins, polyvinyl chloride series resins, polystyrene copolymerresins, amino resins, phenol resins and unsaturated polyester resins andcarbon.

These fillers are in the form of hollow spherical particles.

Examples of the inorganic hollow fillers are glass balloons and silicaballoons.

According to the invention, it is essential to substitute a hollowfiller for a small portion of the total filler.

When employing an organic hollow filler, it is preferably incorporatedto replace 0.5 to 5% by weight of the total filler.

If the amount of substitution is less than 0.5% by weight, the effect ofweight reduction is insufficient.

If the amount of substitution exceeds 5% by weight, also deteriorationof the anti-chipping performance is liable to occur, and economy issacrificed too much.

When employing the inorganic hollow filler, the amount of substitutionis 1 to 30% by weight. A preferred amount of substitution is from 1 to9% by weight.

If the amount of substitution is less than 1% by weight, the effect ofweight reduction is insufficient.

If the amount of substitution is above 9% by weight, on the other hand,wear of the piston section and tip section of coating apparatus areliable to occur.

When employing a combination of organic and inorganic hollow filler, theamount of substitution is from 0.5 to 9% by weight of the overallfiller.

If the substitution amounts are less than the ranges noted above, theeffect of weight reduction is insufficient.

If the substitution amounts are an excess of the ranges noted above, onthe other hand, wear of the piston section and tip section of thecoating apparatus are liable to occur due to reduction of theanti-chipping performance and also due to the inorganic hollow filler.

The hollow fillers employed in accordance with the invention areexpected to have a compressive strength of above 120 kg/cm². If thecompressive strength is lower than about 120 kg/cm² the hollow fillerswill be crushed when the anti-chipping coating is coated using anairless spray or the like.

However, it is possible to employ not only an airless spray but also abrush to coat the coating.

In such a case, the compressive strength of the hollow filler can belower than 120 kg/cm².

The hollow filler employed according to the invention is prepared bycausing flowable plastic or fused glass having a viscosity of 10 to 20poise to discharge and blow out from a nozzle or heating a foamedmaterial in the form of particles or causing the material to foam byfeeding the material into a high temperature air stream.

The grain size of the organic hollow filler may be less than 200μ,preferably of such an order that 95% by weight of the particles of thefiller pass through a 150-mesh sieve (i.e., less than approximately100μ).

The grain size of the inorganic hollow filler may be less than 300μ,preferably of such an order that 95% by weight of the filler particlespass through a 100-mesh sieve (i.e., less than approximately 150μ).

Excessively small grain size will lead to such problems in the airlessspraying as fluctuations of pattern width, clogging of the spray gun andwear of the piston and tip sections thereof.

Also, a coarse finish surface is liable to result.

On the other hand, insufficient grain size will result in reduction ofrupture strength so that it is impossible to obtain the effect of alight weight filler.

The bulk density of the organic hollow filler may be less than 0.1,preferably 0.02 to 0.05.

The bulk density of the inorganic hollow filler may be less than 0.6,preferably 0.2 to 0.5.

The bulk density is preferably as small as possible so long assufficient mechanical strength can be ensured.

According to the invention, it is possible to add a conventionalanti-corrosion agent, dispersing agent, viscosity promoter,anti-freezing agent, pH adjuster and other additives to obtain a lightanti-chipping coating.

An anti-chipping coating of the present invention is light in weightwithout deteriorating at all the anti-chipping performance per unitvolume of coating, can be coated without coating irregularities and canreduce wear of piston section and tip section of coating apparatus.

PREFERRED EMBODIMENTS OF THE INVENTION

In the following Examples and Comparative Examples contained in Tables1-4, the criticality of the hollow filler being present in the specifiedamounts in the anti-chipping coating is illustrated.

In Tables 1-4, "Weight" stands for the weight of the anti-chippingcoating in grams/liter. "Weight reduction ratio" is the amount theweight of the specified anti-chipping coating having hollow fillers isreduced as compared to the weight of the same anti-chipping coatingcomposition not having hollow fillers.

The "Anti-Chipping Property Test" evaluates the anti-chipping propertiesof each coating. This test was performed by coating a test panelconsisting of a cationic series electrodeposition coated steel platehaving dimensions of 0.8 mm by 100 mm by 200 cm with the specifiedanti-chipping coating such that the dry coating film has a thickness of850μ. No occurrences of coating irregularities were found.

After the anti-chipping coating was applied, the panel was baked at 130°C. for 30 minutes and then allowed to sit for 24 hours.

The "nut fall method" disclosed in JASO (Japanese AutomobileStandardization Organization) 7006 was used in the test.

A vinyl chloride pipe with an inner diameter of 20 mm and a length of200 cm was secured in an upright position and the test panel was placedsuch that its coated surface touched the lower end of the vinyl chloridepipe and had a support angle of 60°.

Brass hexagonal nuts having a shape of Class 3 M-4, as defined in JIS(Japanese Industrial Standard) B-181, were allowed to fall from the topof the vinyl chloride pipe. The anti-chipping property was evaluated interms of the total weight in kilograms of nuts that are allowed to falland strike the test panel until the steel surface is exposed.

The "Abrasion ratio" is calculated by first measuring the amount perminute, A, of a first coating that is delivered from a spray gun at aspecified pressure. Then 50 kg of the anti-chipping coating is sprayedthrough the same spray gun. Finally, the amount per minute, B, of thefirst that is delivered from the spray gun at the specified pressure isdetermined.

The "Abrasion ratio" is B/A ×100%.

EXAMPLES 1 TO 6

A polyvinyl chloride resin as a rain component of anti-chipping coating,dioctyl phthalate (DOP) as a plasticizer, calcium carbonate as a filler,carbon black as a coloring agent, a dispersing agent and an organichollow filler trademark "Expancel DE", dried and expanded microspheresof vinylidene chloride/acrylonitrile copolymers containing isobutane asa blowing agent and produced by Nippon Fillite Co., Ltd.) were employedin the charging proportion ratio as shown in Table 1.

Each composition was kneaded in a 4-liter can to obtain anti-chippingcoating.

The results are shown in Table 1.

EXAMPLES 7 TO 11

Inorganic hollow filler available as "Glass Bubbles B37/2000" (a tradename; produced by Sumitomo 3M Co., Ltd.) was employed in lieu of theorganic hollow filler used in Examples 1 to 6 to obtain lightanti-chipping coatings having compositions as shown in Table 1respectively.

The results are shown in Tables 1 and 2.

EXAMPLES 12 TO 20

"Expancel DE" in Examples 1 to 6 and "Glass Bubbles B37/2000" inExamples 7 to 11 were exployed in lieu of the organic hollow filler inExamples 1 to 6 to obtain light anti-chipping coatings havingcompositions as shown in Table 2 respectively.

The results are shown in Table 2.

COMPARATIVE EXAMPLE 1

The hollow filler in Examples 1 to 20 were excluded, whereby ananti-chipping coating having the composition as shown in Table 3 wasobtained. As can be seen by the results in Table 3, this anti-chippingcoating composition had a weight reduction ratio of 0%.

COMPARATIVE EXAMPLE 2

The hollow organic filler of Examples 1-6 was incorporated into theanti-chipping coating in an amount smaller than the specified amounts ofthe present invention. As can be seen by the results in Table 3, thisanti-chipping coating composition had a "weight reduction ratio" of only7.6%.

COMPARATIVE EXAMPLE 3

The hollow filler in Examples 1 to 6 was incorporated in excess of therange defined according to the invention, whereby an anti-chippingcoating having a composition as shown in Table 3 was obtained. As can beseen by the results in Table 3, this anti-chipping coating compositionhad an "anti-chipping property test result" of only 57 kg.

COMPARATIVE EXAMPLE 4

The hollow filler in Examples 7 to 11 was incorporated in ananti-chipping coating in an amount less than the range defined accordingto the invention, whereby an anti-chipping coating having thecomposition as shown in Table 3 was obtained. As can be seen by theresults in Table 3, this anti-chipping coating composition had a "weightreduction ratio" of only 9.7%.

As is obvious from Tables 1 and 2, with the light anti-chipping coatingsof Examples 1 to 20 according to the present invention, it is possibleto reduce the volume of coating to 20 to 40% of the prior art valuewhile providing excellent anti-chipping property comparable to that ofthe prior art anti-chipping coating of Comparative Example 1.

Further, the tip section of the coating apparatus used in Examples 1 to20 and Comparative Examples 1 to 13 was inspected after coating toreveal that it was extremely worn out in the case of ComparativeExamples 5 and 9.

                                      TABLE 1                                     __________________________________________________________________________                           Examples                                                                      1   2   3   4   5   6   7   8   9   10                 __________________________________________________________________________    Polyvinyl chloride resin                                                                    (Parts by Weight)                                                                      100 100 100 100 100 100 100 100 100 100                DOP           (Parts by Weight)                                                                       90 100 100 100 120 120 100 120 120 120                Calcium Carbonate                                                                           (Parts by Weight)                                                                      160 150 150 150 150 150 150 150 150 140                Carbon black  (Parts by Weight)                                                                       1   1   1   1   1   1   1   1   1   1                 EXPANSEL DE   (Wt %)    0.5                                                                               1   2   3   4   5  --  --  --  --                 GLASSBUBBLE B37/2000                                                                        (Wt %)   --  --  --  --  --  --   1   3   5   7                 Dispersing agent                                                                            (Parts by Weight)                                                                       5   5   5   5   5   5   5   5   5   5                 Weight        (g/l)    1280                                                                              1190                                                                              1080                                                                              1050                                                                              1020                                                                              990 1270                                                                              1220                                                                              1190                                                                              1180               Weight reduction ratio.sup.(1)                                                              (%)      11.1                                                                              17.4                                                                              25.0                                                                              27.1                                                                              29.2                                                                              31.3                                                                              11.8                                                                              15.3                                                                              17.4                                                                              18.1               Anti-Chipping property Test                                                                 (kg)      65  63  62  62  62  61  64  64  64  63                Abrasion ratio.sup.(2)                                                                      (%)      102 103 103 103 104 105 105 105 106 107                __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________                           Examples                                                                      11  12  13  14  15  16  17  18  19  20                 __________________________________________________________________________    Polyvinyl chloride resin                                                                    (Parts by Weight)                                                                      100 100 100 100 100 100 100 100 100 100                DOP           (Parts by Weight)                                                                      120  90  90  90  90 120 120 120 120 120                Calcium Carbonate                                                                           (Parts by Weight)                                                                      140 160 160 160 160 150 150 150 150 150                Carbon black  (Parts by Weight)                                                                       1   1   1   1   1   1   1   1   1   1                 EXPANSEL DE   (Wt %)   --  0.1 0.2 0.3 0.4  1   2   3   4   5                 GLASSBUBBLE B37/2000                                                                        (Wt %)    9  0.4 0.3 0.2 0.1  8   7   6   5   4                 Dispersing agent                                                                            (Parts by Weight)                                                                       5   5   5   5   5   5   5   5   5   5                 Weight        (g/l)    1170                                                                              1290                                                                              1290                                                                              1280                                                                              1280                                                                              1170                                                                              1060                                                                              1030                                                                              1000                                                                              970                Weight reduction ratio                                                                      (%)      18.8                                                                              10.4                                                                              10.4                                                                              11.1                                                                              11.1                                                                              18.8                                                                              26.4                                                                              28.5                                                                              30.6                                                                              32.6               Anti-Chipping property Test                                                                 (kg)      63  65  65  66  66  62  63  63  62  62                Abrasion ratio                                                                              (%)      108 103 103 102 102 108 108 107 107 106                __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________                           Comparative Examples                                                          1   2   3   4   5   6   7   8   9   10                 __________________________________________________________________________    Polyvinyl chloride resin                                                                    (Parts by Weight)                                                                      100 100 100 100 100 100 100 100 100 100                DOP           (Parts by Weight)                                                                       90  90 120 100 120  90  90  90 120 120                Calcium Carbonate                                                                           (Parts by Weight)                                                                      160 160 150 150 140 160 160 160 140 140                Carbon black  (Parts by Weight)                                                                       1   1   1   1   1   1   1   1   1   1                 EXPANSEL DE   (Wt %)   --  0.4  6  --  --  0.1 0.2 0.3  1   2                 GLASSBUBBLE B37/2000                                                                        (Wt %)   --  --  --  0.9  10 0.3 0.2 0.1  9   8                 Dispersing agent                                                                            (Parts by Weight)                                                                       5   5   5   5   5   5   5   5   5   5                 Weight        (g/l)    1440                                                                              1330                                                                              970 1300                                                                              1160                                                                              1360                                                                              1350                                                                              1340                                                                              1100                                                                              1060               Weight reduction ratio                                                                      (%)       0  7.6 32.6                                                                              9.7 19.4                                                                              5.6 6.3 6.9 23.6                                                                              26.4               Anti-Chipping property Test                                                                 (kg)      66  65  57  64  58  63  64  65  58  58                Abrasion ratio                                                                              (%)      102 102 105 105 111 103 102 102 109 108                __________________________________________________________________________

                  TABLE 4                                                         ______________________________________                                                           Comparative Examples                                                          11    12      13                                           ______________________________________                                        Polyvinyl chloriden                                                                       (Parts by Weight)                                                                          100     100   100                                    resin                                                                         DOP         (Parts by Weight)                                                                          120     120   120                                    Calcium Carbonate                                                                         (Parts by Weight)                                                                          140     140   140                                    Carbon black                                                                              (Parts by Weight)                                                                           1       1     1                                     EXPANSEL DE (Wt %)        3       4     5                                     GLASSBUBBLE (Wt %)        7       6     5                                     B37/2000                                                                      Dispersing agent                                                                          (Parts by Weight)                                                                           5       5     5                                     Weight      (g/l)        1030    1000  960                                    Weight reduction                                                                          (%)          28.5    30.6  33.3                                   ratio                                                                         Anti-Chipping                                                                             (kg)          57      57    57                                    property Test                                                                 Abrasion ratio                                                                            (%)          108     107   107                                    ______________________________________                                    

What is claimed is:
 1. A light, anti-chipping coating consisting essentially of a blend of 100 parts by weight of a polyvinyl resin capable of forming a plastisol, 50 to 200 parts by weight of a plasticizer for said resin, 2 to 20 parts by weight of additives and 80 to 350 parts by weight of a filler component, said filler component consisting of from 0.5 to 5% by weight of expanded thermoplastic microspheres and the balance being solid calcium carbonate filler powder.
 2. A light, anti-chipping coating consisting essentially of a blend of 100 parts by weight of a polyvinyl resin capable of forming a plastisol, from 50 to 200 parts by weight of a plasticizer for said resin, from 2 to 20 parts by weight of additives and 80 to 350 parts by weight of filler component, said filler component consisting of from 0.5 to 5% by weight, based on the weight of said filler component, of vinylidene chloride/acrylonitrile copolymer, hollow, filler particles and the balance being solid calcium carbonate filler powder.
 3. A coating as claimed in claim 1, in which said plasticizer is dioctyl phthalate and is present in an amount of 100 parts by weight, said solid filler powder is present in an amount of 150 parts by weight, said organic, hollow, filler particles are present in an amount of 1% by weight and said additives are carbon black and a dispersing agent and are present in an amount of 1 part by weight and 5 parts by weight, respectively.
 4. A coating as claimed in claim 1, in which said plasticizer is dioctyl phthalate and is present in an amount of 100 parts by weight, said solid filler powder is present in an amount of 150 parts by weight, said organic, hollow, filler particles are present in an amount of 3% by weight and said additives are carbon black and a dispersing agent and are present in an amount of 1 part by weight and 5 parts by weight, respectively.
 5. A coating as claimed is claim 1 in which said filler component has a particle size of less than 200μ and has a bulk density of less than 0.1
 6. A light, anti-chipping coating consisting essentially of a blend of 100 parts by weight of a polyvinyl chloride resin capable of forming a plastisol, 50 to 200 parts by weight of a plasticizer for said resin, 2 to 20 parts by weight of additives and from 80 to 350 parts by weight of filler component, said filler component consisting of (1) a member selected from the group consisting for from 1 to 9% by weight of glass or silica, hollow, filler particles, from 0.5 to 5% by weight of vinylidene chloride/acrylonitrile copolymer, hollow, hollow, filler particles, and from 0.5% to 9% by weight of glass or silica and vinylidene chloride/acrylonitrile copolymer, hollow, filler particles, said weight of said filler particles being based on the weight of said filler component, and (2) the balance being solid calcium carbonate filler powder. 